Pentax 57233 Digital Camera User Manual


 
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ADVANCED OPERATION FOR THE BUILT-IN FLASH
4.Metered Manual Mode
When using the built-in flash in the Metered Manual Mode,
any combination of aperture and shutter speed 1/125 or
slower can be set. In this mode, the exposure of the
background can be controlled by the manual exposure to
take a flash photograph.
1. Calculating the flash effective range according to the camera-
to-subject distance.
Maximum flash distance = Guide Number ÷ Selected aperture
Minimum flash distance = Maximum flash distance ÷ 5*
*The value 5 used in the formula above is a fixed value applied to the
built-in flash in this camera.
MEMO
When the distance to the subject is less than 0.7m (2.3ft), the flash
cannot be used. If the flash is used within 0.7m, it causes vignetting in
the picture corners, light is distributed unevenly and the picture may be
over exposed.
The guide number (GN) depends upon the film speed used as
shown below.
ISO25 GN5.5 ISO200 GN15.6
ISO50 GN7.8 ISO400 GN22
ISO100 GN11